In general, this invention relates to motion analysis systems and more particularly, this invention relates to motion analysis systems in which images from two video imagers are recorded and reproduced in interleaved format.
Motion analysis of fast moving phenomena in slow motion entails the recording of a great number of images during an event at high speed, and then playing the images back slowly to analyze the movement which has occurred in step-by-step progression. Applications for motion analysis include malfunctions in high speed machinery, movements of an athlete, failure of safety equipment, shattering of an object and physical reactions to a tire hitting a pothole at high speed. One type of motion analyzer is the SP 2000 Motion Analysis System available from the Spin Physics Division of the Eastman Kodak Co. This system includes a video camera, a variable speed magnetic tape processor and a cathode ray tube (CRT) display monitor. The camera is capable of producing signals corresponding to selected frame rates of from 60 to about 2000 frames per second. The video is read out from the imager in block format, i.e., a plurality of lines of video simultaneously and is recorded in sequential blocks on a plurality of longitudinal tracks on tape. The magnetic tape processing system is capable of recording at one tape speed and appropriately slowing down the tape during playback to a certain predetermined speed to down convert the camera signals regardless of the camera frame rate, to a nominal frame rate of 30 or 60 frames per second. The CRT display monitor receives the second frame rate playback signal from the magnetic tape processing system and displays the scene in question at an appropriate slow motion, depending upon the selected camera frame rate.
The SP 2000 Motion Analysis System can record (1) all of the frames from one imager; (2) all of the frames from the other imager and (3) a frame which is a composite of part of a frame from one imager overlayed with a frame from the other imager. Although this system eminently satisfies the applications for which it is designed, there are certain applications where the need arises to record full frames from each imager simultaneously. The overlay technique does not satisfy this need since image areas from both frames are deleted in the recorded composite frame and it is sometimes desirable to have the deleted areas available for viewing. Using two motion analysis systems to effect recording of full frames from both imagers is costly and complex.